Printing processes, such as the lithographic web offset process, commonly use an arrangement of rollers called an inker to accept ink from an ink metering device and deliver it to a printing plate. A goal of the inker is to supply the plate with a thin, uniform film of ink. An inker may contain as many as twenty rollers to achieve this goal.
One reason for the large number of rollers in an inker is that the ink feed from prior art ink metering devices, such as ink fountains, ductors, and metering rolls, is intermittent. Typically the ink is supplied by the ink metering device in the form of stripes or spots spaced about two or more inches apart in the circumferential direction on the first inker roll. An inker contains extra rollers to filter out these spots or stripes so that the plate receives a uniform ink film and the spots or stripes do not appear in the print.
To produce a high quality printed product, most ink metering devices allow the feed rate of ink into the inker to be varied laterally across the web or sheet. Typically the metering device is divided into separate lateral zones about one or two inches in width, with the ink feed in each zone being separately controllable.
Printing processes, such as the lithographic web offset process, commonly use an arrangement of rollers called a dampener. The goal of the dampener is to deliver a thin, uniform film of dampening fluid to a printing plate. Typical prior art dampeners are of two basic types, generally called spray dampeners and pan-roll dampeners. Spray dampeners typically have the dampening fluid sprayed onto the first dampener rollers. Pan-roll dampeners typically transfer the dampening fluid onto the first dampener rollers from a pan-roller which is partially submerged in a pan containing dampening fluid.
To transfer more or less dampening fluid on a localized lateral area of the lithographic printing plate, the typical pan-roll dampeners has only roller-squeeze and roller-skew for coarse adjustments. The typical spray dampener accomplishes lateral control for localized areas by varying the fluid flow rate through laterally spaced spray nozzles. The typical spray dampeners also have over-spray issues and rely on the sprayed fluid to adhere to the dampener rollers.
Printing processes, such as the flexographic printing process, commonly use an engraved anilox roller to deliver a quantity of ink from an ink chamber to a flexographic printing plate. The raised image sections of the flexographic printing plate then transfer a portion of the ink delivered by the anilox roll to the substrate being printed.
The goal of the anilox roller is to supply the flexographic printing plate a quantity of ink proportional to the volume of the engraved anilox cells. The goal of the flexographic printing plate is to selectively transfer a portion of the ink delivered by the anilox roll to the printing substrate.
To transfer more or less ink on a localized lateral area of the substrate being printed, typically the flexographic printing plate is replaced by another flexographic printing plate having a larger or smaller image transfer areas.
To transfer more or less ink laterally uniform across the substrate being printed, typically the engraved anilox roller is replaced by another engraved anilox roller having a larger or smaller engraved anilox cell volume.